EP4300121A1 - Dispositif d'imagerie par résonance magnétique comportant un ensemble bobine de gradient - Google Patents

Dispositif d'imagerie par résonance magnétique comportant un ensemble bobine de gradient Download PDF

Info

Publication number
EP4300121A1
EP4300121A1 EP22181853.7A EP22181853A EP4300121A1 EP 4300121 A1 EP4300121 A1 EP 4300121A1 EP 22181853 A EP22181853 A EP 22181853A EP 4300121 A1 EP4300121 A1 EP 4300121A1
Authority
EP
European Patent Office
Prior art keywords
gradient
coil assembly
gradient coil
main
longitudinal
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP22181853.7A
Other languages
German (de)
English (en)
Inventor
Peter Dietz
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Siemens Healthineers AG
Original Assignee
Siemens Healthcare GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Siemens Healthcare GmbH filed Critical Siemens Healthcare GmbH
Priority to EP22181853.7A priority Critical patent/EP4300121A1/fr
Priority to US18/216,037 priority patent/US20240004010A1/en
Publication of EP4300121A1 publication Critical patent/EP4300121A1/fr
Pending legal-status Critical Current

Links

Images

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
    • G01R33/38—Systems for generation, homogenisation or stabilisation of the main or gradient magnetic field
    • G01R33/385—Systems for generation, homogenisation or stabilisation of the main or gradient magnetic field using gradient magnetic field coils
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
    • G01R33/38—Systems for generation, homogenisation or stabilisation of the main or gradient magnetic field
    • G01R33/385—Systems for generation, homogenisation or stabilisation of the main or gradient magnetic field using gradient magnetic field coils
    • G01R33/3852—Gradient amplifiers; means for controlling the application of a gradient magnetic field to the sample, e.g. a gradient signal synthesizer
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
    • G01R33/38—Systems for generation, homogenisation or stabilisation of the main or gradient magnetic field
    • G01R33/385—Systems for generation, homogenisation or stabilisation of the main or gradient magnetic field using gradient magnetic field coils
    • G01R33/3856—Means for cooling the gradient coils or thermal shielding of the gradient coils
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
    • G01R33/38—Systems for generation, homogenisation or stabilisation of the main or gradient magnetic field
    • G01R33/381—Systems for generation, homogenisation or stabilisation of the main or gradient magnetic field using electromagnets
    • G01R33/3815—Systems for generation, homogenisation or stabilisation of the main or gradient magnetic field using electromagnets with superconducting coils, e.g. power supply therefor
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
    • G01R33/42—Screening
    • G01R33/421—Screening of main or gradient magnetic field
    • G01R33/4215—Screening of main or gradient magnetic field of the gradient magnetic field, e.g. using passive or active shielding of the gradient magnetic field

Definitions

  • the invention concerns a magnetic resonance imaging device, comprising
  • the main field (also main magnetic field B0) is generated by a superconducting main field coil assembly.
  • the superconducting main field coil assembly is located in cryogenic assembly, in particular a cryostat, of the magnetic resonance imaging device, usually comprising an outer vacuum vessel (or outer vacuum container, OVC), a thermal shield (often called cryogenic shield or, shortly, cryo-shield) and an inner cooling medium vessel or chamber comprising a cooling medium, for example helium, and the superconducting coils of the main field coil assembly.
  • cryogenic assembly in particular a cryostat
  • the magnetic resonance imaging device further comprises a gradient coil assembly, which usually comprises multiple gradient coils adapted to generate a linear magnetic field gradient in a corresponding, in particular cartesian, direction.
  • the cryogenic assembly or the vacuum vessel respectively, define a cylindrical patient bore into which a patient can be introduced using a patient table.
  • the gradient coil assembly is usually provided radially adjacent to the cryogenic assembly in the patient bore, wherein, inside the gradient coil assembly, a radio frequency coil assembly, for example a body coil and/or a birdcage coil, may be located.
  • the longitudinal axis of the patient bore is usually called the Z direction, wherein the vertical direction orthogonal to the longitudinal direction is called the Y direction and the horizontal direction orthogonal to the longitudinal direction is usually called the X direction.
  • Gradient coil assemblies of known magnetic resonance imaging devices often have gradient coils for generating field gradients in the Z direction, the X direction, and the Y direction, respectively.
  • the X direction and the Y direction are usually called transverse directions, such that the X gradient coil and the Y gradient coil are called transversal gradient coils.
  • the purpose of the gradient coils of the gradient coil assembly in magnetic resonance imaging is to produce, in particular dynamic, gradient fields in the homogeneity volume, which corresponds to the field of view of the magnetic resonance imaging device.
  • the gradient coils also produce stray fields, in particular on the radially outer side of the gradient coils. Such stray fields may influence the cryogenic assembly and the superconducting main field coil assembly.
  • the stray fields induce eddy currents in conductive material.
  • Such eddy currents (and hence the stray fields) have two main effects. As a first effect, eddy currents produce ohmic heat, and as a second effect, eddy currents create their own magnetic fields, which may disturb magnetic resonance imaging and are hence called disturbance fields in the following.
  • any unintended magnetic field has the potential to disturb the image quality of magnetic resonance imaging.
  • time varying disturbance fields or more complex spatial variations, in particular of higher order than one are known to cause severe issues, in particular artefacts in magnetic resonance images.
  • a main source of these disturbance fields comprising image quality are the electrically conductive structures intended to shield superconducting coils.
  • local minimization of the stray fields by adapted gradient conductor positioning has been proposed, such that zones of low stray field strength may be created by using areas having a lower conductor density than other areas having a higher conductor density.
  • these approaches have their limitations, for example due to the required linearity of the field gradients in the homogeneity volume.
  • Another aspect to consider is the force compensation of the gradient coils of the gradient coil assembly.
  • a mechanical force on the gradient coil during a magnetic resonance sequence, in particular during pulses should be avoided, since vibration during imaging causes deviations in the generated fields.
  • a main cause of the vibrations are force contributions from magnet inhomogeneities, which add up to cause net forces on a complete gradient coil assembly. Conductors in the vicinity of superconducting coils are usually causing the highest contribution to such disadvantageous net mechanical forces.
  • Force balanced designs usually comprise gradient coil conductors at the longitudinal ends of the gradient coil, which are positioned beyond the longitudinally outermost superconducting coils.
  • Such "force compensation conductors” cause significant stray fields affecting the cryogenic assembly, in particular shielding assemblies or the superconducting coils themselves.
  • the invention exploits the fact that in many designs of main field coil assemblies most of the superconducting material, in this case the main superconducting coils, are positioned in longitudinal end regions of the cryogenic assembly.
  • the at least two main superconducting coils in the longitudinal end regions may comprise the majority of the superconductors of the main field coil assembly.
  • Such main superconducting coils are, however, usually also placed at the radially inner rim of the cryogenic assembly, that is, closest to the longitudinal axis of the patient bore and hence the homogeneity volume.
  • the superconducting coils in the vacuum vessel may be arranged as multiple radial groups in different radial regions, wherein the main superconducting coils usually belong to the radially innermost group.
  • the main field coil assembly may comprise at least two radially consecutive groups of superconducting coils, wherein the main superconducting coils are the longitudinally outermost superconducting coils of the radially innermost group.
  • the inductance of not actively shielded gradient coil assemblies are systematically reduced by about 50% compared to gradient coil assemblies having an active shielding layer. The exact value of reduction of the inductance depends on the distance between the gradient coil and the shielding coils provided by the active shielding layer.
  • no shielding coils for generally shielding conductors have to be powered, such that less electrical energy is needed and less heat is generated in such an unshielded gradient coil assembly.
  • the dogma according to which the region, in particular for return conductors, should be extended as much as possible can be taken back to instead allow the design of a significantly longitudinally shorter gradient coil assembly, in particular by shortening the longitudinal extent of the transversal gradient coils generating field gradients in the transversal directions perpendicular to the longitudinal direction.
  • the short gradient coil assembly may also be advantageous regarding noise generation, since a shorter assembly may be dynamically stiffer and/or may comprise less resonances in the audible frequency region and/or the amplitudes of bending vibrations may be lower.
  • the conductors of the at least one transversal gradient coil comprise windings around a central turning point in a longitudinal-circumferential plane, wherein the windings comprise main conductor segments located on the longitudinal side of the turning point towards the homogeneity volume and return conductor segments on the longitudinal side of the turning point away from the homogeneity volume, wherein the density of return conductor segments is at least 90 % of, in particular at least substantially equal to, the density of main conductor segments in the longitudinal direction.
  • the gradient conductor pattern, in particular gradient wire pattern, of a transversal gradient coil (X or Y) usually comprises two different regions, namely the region generating the relevant gradient fields, which extends from the isocenter (center of patient bore and/or homogeneity region) side to the so-called turning point (around which the windings run), and the region of so-called return conductor segments, in particular return wires, extending from the turning point towards the longitudinal end.
  • the return conductor segments have much less influence on the vital characteristics of a gradient field generated by a gradient coil than the main conductor segments in the longitudinally inner region.
  • preferred embodiments of the invention propose to use a high density of the return conductor segments to reduce the longitudinal extension of the transversal gradient coils and hence the gradient coil assembly.
  • This again breaks with the dogma, as, in the state of the art, in particular for actively shielded gradient coils, design focusses on keeping the density of the return conductor segments as low as possible to reduce inductance and localized heat generation in the gradient coil.
  • no active shielding layer is present in the gradient coil assembly, its inductance and also heat generation are reduced anyway, such that the minor compromises to make when increasing the conductor density do not in the least outweigh the major advantages gained.
  • the longitudinal extension of the return conductor segment arrangement is at least substantially equal to or less than the longitudinal extension of the main conductor segment arrangement. If the return conductor segments are packed as densely as possible, the overall longitudinal extension of the return conductor segment arrangement (or return conductor segment pattern) can be compressed at least to the extension of the region for actual production of the gradient fields, that is, the main conductor segment arrangement (or main conductor segment pattern).
  • the turning point is located at, for example, 25 to 30 cm from the isocenter.
  • an overall longitudinal extension of the gradient coil conductor pattern for the transversal gradient coils of less than 50 cm is possible, such that the longitudinal extension of the whole gradient coil assembly may be less than 1 m.
  • a length of less than or approximately 1 m allows to produce the stray fields of the gradient coil assembly inside the longitudinal conductor region between the two longitudinal end regions, such that no significant amount of energy is deposited in the main superconducting coils located in the longitudinal end regions.
  • the longitudinal length of the gradient coil assembly is 1 m or less than 1 m. While increasing the density of return conductor segments is a preferable approach to achieve this goal, the invention also proposes other approaches to significantly shorten the length of the gradient coil assembly, which can, in preferable embodiments, be combined with the increased density of the return conductor segments to yield an optimal design.
  • the length of the gradient coil assembly comprising conductors may be less than 1.2 m, in particular less than 1 m.
  • the conductors may be wires having a width of less than 3 mm, in particular less than 2 mm, and/or a cross-sectional area of less than 10 mm 2 .
  • the conductors of the gradient coils of the gradient coil assembly are preferably wires, as opposed to thin films or the like, which require a higher spatial extension in the longitudinal-circumferential plane.
  • such wires usually have a cross-sectional area of more than 25 mm 2 , in particular 30 mm 2 or the like, for example at extensions of 6x5 mm. It is now proposed to use smaller wire cross-sections, which significantly contribute to shortening the gradient coil assembly.
  • the magnetic resonance imaging device further comprises a gradient power amplifier for providing current to the gradient coils, wherein the gradient power amplifier has a maximum output current of at least 1000 A, in particular at least 1200 A.
  • a high current gradient power amplifier may be used, in particular in combination with small wire cross-sections and a high density of return conductor segments.
  • the higher the current the higher the possible current density (at smaller longitudinal extension of wires), further contributing to decreasing the longitudinal extension of the transversal gradient coils and hence the gradient coil assembly.
  • higher ohmic heating losses can be expected, which are, however, still lower than when using an actively shielded gradient coil assembly.
  • the not actively shielded gradient coil assembly may further comprise a cooling device designed for cooling an actively shielded, longer gradient coil assembly, which can easily handle the additionally created heat.
  • Fig. 1 is a schematical cross-sectional view of a magnetic resonance imaging device 1 in an embodiment.
  • the magnetic resonance imaging device 1 comprises a cryogenic assembly having an outer vacuum vessel 2, a thermal shield 3 (cryo-shield) and an inner cooling medium vessel, in this case helium vessel, which is not shown in fig. 1 .
  • helium vessel which is not shown in fig. 1 .
  • superconducting coils 4, 5, 6 are supported by the support structure 7.
  • the outer vacuum vessel 2 defines a cylindrical patient bore 8 having a longitudinal direction 9, which is usually called Z direction.
  • the horizontal direction orthogonal to the longitudinal direction 9 is usually called X direction, while the vertical direction orthogonal to the longitudinal direction 9 is usually called Y direction.
  • the superconducting coils 4, 5, 6 of the main field coil assembly generate a main field (main magnetic field, B0), in which the spins of an object to be imaged align.
  • the main field has a certain homogeneity in a homogeneity volume 10, which forms a field of view of the magnetic resonance imaging device 1 and extends around an isocenter 11.
  • a cylindrical gradient coil assembly 12 is provided inside the patient bore 8, wherein the gradient coil assembly 12 comprises three gradient coils, in particular one gradient coil to generate a field gradient in Z direction in the homogeneity volume 10 (Z coil), one gradient coil to generate a magnetic field gradient in the Y direction in the homogeneity volume 10 (Y coil) and one gradient coil to generate a magnetic field gradient in the X direction in the homogeneity volume 10 (X coil).
  • the Y coil and the X coil are also called transversal gradient coils.
  • the gradient coils of the gradient coil assembly 12 are indicated by symbolic conductors 13, 14, wherein the conductors 13 are wires of the Z coil running substantially in circumferential direction and the conductors 14 are wires of the transversal gradient coils which run in a more complex pattern as discussed in more detail below.
  • a radio frequency coil assembly may also be provided, for example a body coil and/or a birdcage coil.
  • a radio frequency coil assembly as well as other elements of the magnetic resonance imaging device 1, for example cover elements, the patient table and the like, are, for simplicity, not shown in the figures to focus onto the respective designs of the superconducting main field coil assembly and the gradient coil assembly 12.
  • the superconducting main field coil assembly comprises multiple superconducting coils 4, 5, 6 arranged symmetrically in pairs (two main superconducting coils 4, two superconducting coils 5 and two superconducting coils 6) regarding the longitudinal direction 9.
  • Two radially offset groups of superconducting coils 4, 5 and 6 are shown, namely an inner radial group of superconducting coils 4 and 6 and an outer radial group of superconducting coils 5.
  • the outer radial group is significantly farther away from the gradient coil assembly 12, such that stray fields of the gradient coil assembly 12 will be very weak, in particular negligible, such that the following considerations put lesser weight the outer radial group or even classify the superconducting coils 5 as irrelevant.
  • the superconducting coils 4 are main superconducting coils 4, since they comprise the majority of the superconductors of the main field coil assembly and hence generate the highest portion of the main field in the homogeneity volume 10. Such main superconducting coils 4 are usually positioned in opposing longitudinal end regions 15 of the cryogenic assembly. To reduce the amount of stray fields impacting the superconducting coils 4 (and here also 5) in the longitudinal end regions 15, the gradient coil assembly 12 has been designed such that it does not extend into the longitudinal end regions 15, but only in a longitudinal conductor region 16 between the two longitudinal end regions 15, at least concerning the conductors 13, 14. In particular, the gradient coil assembly 12 is shorter in the longitudinal direction 9 than the vacuum vessel 2, in particular by at least twice the longitudinal size of the longitudinal end regions 15. In concrete embodiments, the longitudinal extension of the gradient coil assembly 12 may be less than 1 m.
  • the gradient coil assembly 12 is not actively shielded, i.e. comprises no active shielding layer. Since the extension of the conductor patterns of the gradient coil assembly 12 is very short longitudinally, it will not generate strong stray fields on the main superconducting coils 4 in the longitudinal end regions 15. Here, the conductor pattern ends short of the position of the main superconducting coils 4 such that the amount of heat deposited in the superconducting coils 4 (or a passive shielding assembly, for example at the thermal shield 3) is dramatically reduced. In addition, force balancing is not required, such that no conductors are required at far out longitudinal positions, again reducing the stray field load on the superconducting coils 4 (and 5). Generally, the stray field load onto the ends of the magnet (cryogenic assembly and main field coil assembly) is reduced, in turn decreasing the risk of image artefacts.
  • the discussed design works well with a segmented shielding assembly in the cryogenic assembly. While, in the past, it has been proposed to form the thermal shield 3 or other components of the cryogenic assembly completely of an electrically conducting material having a high electrical conductivity, due to the placement of the superconducting coils 4, 5, 6 longitudinally and radially extending transparency regions result, where stray fields do not meet superconducting material such that local shielding may not be necessary in such transparency regions. Hence, for example, conductive shielding rings for passively shielding at least the superconducting coils 4, 6 may be locally provided overlaying these superconducting coils 4, 6. Active shielding, however, is not required.
  • a high density of return conductor segments of the conductors 14 of the transversal gradient coils is implemented, as illustrated schematically in fig. 2 , showing a representative portion of a conductor pattern of a transversal gradient coil of the gradient coil assembly 12. It is noted that this is purely schematical regarding the number of conductors 14 and their course.
  • the conductors 14 run around a turning point 17 in the longitudinal direction 9, wherein on the longitudinal side 18 of the turning point 17 towards the homogeneity volume 10 and isocenter 11, main conductor segments 19 extend which create the relevant gradient fields in the homogeneity volume 10.
  • return conductor segments 21 extend, which have significantly less influence onto the shape of the gradient field in the homogeneity volume 10.
  • the return conductor segments 21 are packed as densely as possible in the longitudinal direction 9, in particular such that the conductor density of the return conductor segments 21 in the longitudinal direction 9 is equal to or even higher than the conductor density of the main conductor segments 19 in the longitudinal direction 9.
  • the longitudinal extension of the respective main conductor segment pattern may be comparable to or even greater than the return conductor segment pattern.
  • the conductor segments 19, 21, in this case wire segments have been designed with a small wire cross-section as shown in fig. 3 , such that they can be packed even more densely.
  • the wire 22 shown in fig. 3 has a longitudinal extension 23 of equal to or even less than 2 mm, wherein the radial extension 24 can be chosen accordingly, for example also as 2 mm.
  • the wires 22 can be made of copper or aluminum.
  • the magnet resonance imaging device 1 comprises a gradient power amplifier 25 only schematically shown in fig. 1 .
  • the gradient power amplifier 25 is configured to provide current of up to 1200 A to the gradient coils of the gradient coil assembly 12.
  • a gradient coil assembly 12 may have a higher inductance and produce more ohmic heating than gradient coils using known conductor patterns, heating and inductance are still less than in a gradient coil assembly additionally having an active shielding layer.
  • known cooling devices may be applied to the gradient coil assembly 12, in particular cooling devices which have been designed/dimensioned for a gradient coil assembly having an active shielding layer.

Landscapes

  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Magnetic Resonance Imaging Apparatus (AREA)
EP22181853.7A 2022-06-29 2022-06-29 Dispositif d'imagerie par résonance magnétique comportant un ensemble bobine de gradient Pending EP4300121A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP22181853.7A EP4300121A1 (fr) 2022-06-29 2022-06-29 Dispositif d'imagerie par résonance magnétique comportant un ensemble bobine de gradient
US18/216,037 US20240004010A1 (en) 2022-06-29 2023-06-29 Magnetic Resonance Imaging Device with a Gradient Coil Assembly

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP22181853.7A EP4300121A1 (fr) 2022-06-29 2022-06-29 Dispositif d'imagerie par résonance magnétique comportant un ensemble bobine de gradient

Publications (1)

Publication Number Publication Date
EP4300121A1 true EP4300121A1 (fr) 2024-01-03

Family

ID=82492309

Family Applications (1)

Application Number Title Priority Date Filing Date
EP22181853.7A Pending EP4300121A1 (fr) 2022-06-29 2022-06-29 Dispositif d'imagerie par résonance magnétique comportant un ensemble bobine de gradient

Country Status (2)

Country Link
US (1) US20240004010A1 (fr)
EP (1) EP4300121A1 (fr)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5296810A (en) * 1992-03-27 1994-03-22 Picker International, Inc. MRI self-shielded gradient coils
US5474069A (en) * 1993-01-19 1995-12-12 The Mcw Research Foundation, Inc. NMR local coil for brain imaging
US5783943A (en) * 1996-11-27 1998-07-21 Mastandrea, Jr.; Nicholas J. Method and apparatus for positioning an insert gradient coil within an examination region of a magnetic resonance imaging apparatus
US20100226058A1 (en) * 2009-03-03 2010-09-09 Siemens Plc Method for Progressively Introducing Current into a Superconducting Coil Mounted on a Former
US20140225610A1 (en) * 2013-02-12 2014-08-14 Stefan Popescu Magnetic resonance system with pulsed compensation magnetic field gradients

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5296810A (en) * 1992-03-27 1994-03-22 Picker International, Inc. MRI self-shielded gradient coils
US5474069A (en) * 1993-01-19 1995-12-12 The Mcw Research Foundation, Inc. NMR local coil for brain imaging
US5783943A (en) * 1996-11-27 1998-07-21 Mastandrea, Jr.; Nicholas J. Method and apparatus for positioning an insert gradient coil within an examination region of a magnetic resonance imaging apparatus
US20100226058A1 (en) * 2009-03-03 2010-09-09 Siemens Plc Method for Progressively Introducing Current into a Superconducting Coil Mounted on a Former
US20140225610A1 (en) * 2013-02-12 2014-08-14 Stefan Popescu Magnetic resonance system with pulsed compensation magnetic field gradients

Also Published As

Publication number Publication date
US20240004010A1 (en) 2024-01-04

Similar Documents

Publication Publication Date Title
EP0138270B1 (fr) Appareil à résonance magnétique nucléaire
US5280247A (en) Filamentary cold shield for superconducting magnets
JPH03133428A (ja) 核スピントモグラフィ装置用テセラルグラジエントコイル
EP0826977B1 (fr) Aimant supraconducteur d'IRM compact
JP5805655B2 (ja) 核磁気共鳴イメージングに用いられるオープンボア型磁石
US7141974B2 (en) Active-passive electromagnetic shielding to reduce MRI acoustic noise
JP4421079B2 (ja) Ｍｒｉ用傾斜磁場コイル
CN107621615A (zh) 嵌入式梯度及射频集成线圈及带有该集成线圈的磁共振设备
JP2019141226A (ja) 傾斜磁場コイル
US7230426B2 (en) Split-shield gradient coil with improved fringe-field
EP4300121A1 (fr) Dispositif d'imagerie par résonance magnétique comportant un ensemble bobine de gradient
AU2019396124B2 (en) Gradient coil system
US5864235A (en) Nuclear magnetic resonance tomography apparatus with a combined radio-frequency antenna and gradient coil structure
US20170276748A1 (en) Force reduced magnetic shim drawer
GB2323207A (en) Flexible hollow electrical cable
US12099104B2 (en) Passive shield for magnetic resonance imaging gradient coils
EP4300122A1 (fr) Dispositif d'imagerie par résonance magnétique et procédé de conception d'un ensemble de protection pour un dispositif d'imagerie par résonance magnétique
RU2782979C2 (ru) Катушка экранирования градиентного магнитного поля с меандровой обмоткой для устройства магнитно-резонансной томографии
US11255935B2 (en) Gradient shield coil with meandering winding for a magnetic resonance imaging apparatus
WO2023011128A1 (fr) Systèmes d'imagerie par résonance magnétique et composants de ceux-ci
US20240077557A1 (en) Superconducting magnet and mri apparatus
Sattarov et al. New magnet technology for a 1.5 T open-MRI breast imager
Thekkethil et al. Effect of Thermal Strain, Induced by Cryogenic Cooling, on a High Homogeneity Superconducting Magnet for MRI Applications
JP2010046495A (ja) Ｍｒｉ用傾斜磁場コイルの設計方法

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION HAS BEEN PUBLISHED

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

RAP1 Party data changed (applicant data changed or rights of an application transferred)

Owner name: SIEMENS HEALTHINEERS AG

17P Request for examination filed

Effective date: 20240619

RBV Designated contracting states (corrected)

Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR